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Particle Physics

We study the constituents of matter and their fundamental interactions using data of the Compact Muon Solenoid (CMS) experiment. Our studies range from the study of the top quark and the Higgs boson to the search for new phenomena beyond the standard model. Our group also contributes to technical areas like the calibration of the jets and missing transverse momentum, support of the german NAF and the development and maintenance of the reconstruction and analysis software. In addition, we are involved in the Gfitter project. (image source: CMS/CERN)

The Large Hadron Collider (LHC) at CERN provides proton-proton collisions at high centre of mass energies and luminosity. Both, the centre of mass energy of 7-14 TeV and the luminosity of the LHC by far exceed those of previous colliders offering a huge physics potential. Our group participates in the Compact Myon Solenoid Experiment (CMS), wich succesfully found the Higgs particle as the last missing piece of the Standard Model (SM), and searches for possible extensions of the SM, like supersymmetry or extra spatial dimensions, up to mass scales of several TeV. (image source: CMS/CERN)

Supersymmetry (SUSY) is a well motivated extension of the Standard Model (SM), introducing a new fundamental symmetry between fermions and bosons. It provides elegant solutions to a series of shortcomings of the SM, such as the Dark Matter problem. Thus SUSY provides a link between microscopic particle physics and large scale cosmology. An important SUSY prediction is the existence of new particles, which could have masses up to a few TeV and are therefore in the reach of the LHC. We search for signatures of these new particles in various final states with the CMS experiment. (image source: CMS/CERN)

The top quark is the heaviest elementary particle in the Standard Model. At the LHC, top quarks are copiously produced and their properties (production mechanisms, mass, charge) can therefore be measured with unprecedented accuracy. Such measurements are, in the first place, necessary to test Standard Model predictions based on calculations in perturbative quantum chromodynamics (QCD). However, due to its large mass, it is expected that the top quark also plays an important role in various possible scenarios beyond the Standard Model. Top quark physics provides thus a window to new physics. (image source: CMS/CERN)

It is known since a long time that the Standard Model of particle physics can not be the complete theory of the fundamental building blocks of nature. In the past, hints for new physics theories beyond the SM (BSM) have been searched for at all high-energy colliders. With the enormous center-of-mass energy of the Large-Hadron-Collider (LHC) at CERN a completely unexplored energy regime can be studied now. In particular the mass region around 1 TeV, where hints for new physics are expected, has become experimentally accessible. Our group contributes to this quest in several important areas, from the search of a fourth fermion generation to the search for new heavy particles decaying to top quarks. (image source: CMS/CERN)

For a long time, the Higgs boson was one of the missing pieces of the Standard Model (SM). It has been predicted in 1964 as a consequence of a mechanism which explains the masses of the known particles. In July 2012, the discovery of a Higgs-like particle has been announced by the ATLAS and CMS experiment. Since then, many of the properties of this particle have been studied by the CMS collaboration strengthening the believe that the new particle is indeed the long search Higgs boson of the SM. (image source: CMS/CERN)

The wealth of data from particle physics experiments provides important constraints on the Standard Model and possible extensions thereof. The full potential of these data can only be exploited in a global interpretation in the context of a given theoretical framework. Our group is involved in the development of Gfitter, which is a generic fitting framework which can be used for a global interpretation of experimental data, such as the Standard Model fit to electroweak precision data.